Method for treating mercury mines



Patented Nov. 3, 1942 I 2,aoo.9s METHOD ron rnna'rmc'rmnctm MINES Merle aaiiaau, Berkeley, Calif.

No Drawing. Application June 23, 1941, Serial No. 399,417

Claims.

This invention relates to a method of and means for treating mercury mines.

an important object of my invention is to make it possible to operate mercury mines in which free mercury occurs without causing a health hazard due to the presence of mercury vapor in the atmosphere of the mine.

A further important object of my invention is to make it possible to decrease the health hazard in mercury mines, the walls of which are impregnated with liquid mercury or liquid mercury,

' result of blasting or other operations, or when free mercury dust is present on the timbers or the walls, then the evaporation of the mercury from the surface of the particles of liquid mercury and/or dust causes the concentration of mercury vapor in the air of the mine to rise to levels sufiicient to cause a serious health hazard to the workers therein. Increasing the rate of ventilation may not sufiice to decrease the concentration, and such increase in ventilation has actually been known to increase the mercury vapor concentration in some cases.

I have found that when the faces, muck piles, walls, timbers, stopes, tunnels, and other parts of a mercury mine exposed to dust from the blasting and drilling operations, or opened as a result of the blasting operations, were sprayed with an alkali polysulfide solution, preferably with a'spreader and adhesive or fixative, the concentration of the mercury vapor in the air was reduced to barely determinable concentrations. For example, when a mine containing approximately 16 milligrams of mercury vapor per ten cubic meters of air was so treated the mercury vapor concentration was so reduced that there was no noticeable blackening of selenium sulfide paper on five hours exposure in the conventional apparatus made for this purpose or to less than 0.5 milligram per ten cubic half gallons of 29 per cent by weight solution 55 per gallons of spray solution. Sodium or potassium or any of the other alkali or alkaliearth polysulfides including ammonium or substituted ammonium polysulfldes or a mixture of these may be used, and I use the term alkali polysulfide" to include any and all of the above compounds.

The preferred spreader is one formed by the process disclosed in U. S. Patent No. 1,922,607 to Volck, together with casein, ammonia soap and cresylic acid. The product of the patent is an organic sulfur acid component from relatively heavy mineral oils which consists in reacting these oils with sulphuric acid at controlled temperatures. The spreader is used to the extent of one pint per 100 gallons of spray material. Any other suitable spreader or wetting agent may be used, the purpose oi which is to cause the timbers, rock faces, etc., to become more readily uniformly covered with the treating spray, and I have used the words spreader and spreading agent to cover such a material.

The preferred adhesive or fixative has a petro- 5 leum base containing emulsifiable oils of the light lubricating oil class. Any other suitable adhesive may be used, the purpose of which is to assist in maintaining the alkali polysulfide film intact and to materially reduce the caustic properties of the polysulfide solution to the operators of the process, and I have used those terms to define such a material.

Wettable sulfur to the extent of five pounds per 100 gallons of solution is also of great value in enabling the operator to see the parts that have been previously sprayed. A dye may be added to the spray for the same purpose. The Wettable sulfur also assists to maintain a very slight vapor pressure of sulfur which will combine with any mercury vapor which penetrates the alkali polysulfide film or evaporates from parts not reached by the spray.

A small portion of glycerine-less than one per cent of total solution-or other highly hygroscnpic substance may be added to the spray solution for the purpose of maintaining a moist condition in the deposited film, if desired.

The concentration of the constituents of the spray solution may be vvaried over wide limits.

While I have disclosed the use of various substances which may be used with the alkali polysulfide, satisfactory reduction of the mercury vapor concentration may be achieved without the use of any of said additional substances. For example, satisfactory reduction of the mercury vapor concentration may be obtained by thoroughly wetting all of the surfaces of the mine with a three per cent (3%) by weightsolution of sodium polysulfide. The spreader and the adhesive substances may or may not be added as desired.

The mixture is preferably mixed and sprayed on all of the faces, muck piles, walls, timbers, stopes, tunnels and other parts of the mine and in sufficient quantities to thoroughly Wet all surfaces.

From the foregoing description, the uses, advantages, and 'operation of my invention will be readily understood by those skilled in the art to which the invention appertains. While I have described certain examples of my invention, I desire to have it understood that the examples given are merely illustrative, and that the invention is not to be limited to the details disclosed herein, but is to be accorded the full scope of the appended claims.

I claim: i

1. A method of treating mercury mines comprising spraying a water solution of alkali polysulfide on the surfaces of said mine.

2. A method of treating mercury mines comprising spraying an aqueous mixture of an alkali polysulfide and a spreading agent on the surfaces of said mine.

3.v A method of treating mercury mines comprising spray an aqueous mixture of an alkali polysulflde and an adhesive on the surfaces of said mine.

4. A method of treating mercury mines comprising spraying an aqueousmixtureof an alkali polysulflde and wettable sulfur on the surfaces of said mine.

5. A method of treating mercury mines comprising spraying an aqueous mixture of an alkali polysulfide, a spreading agent, an adhesive and wettable sulfur on the surfaces of said mine.

6. A method of treating mercury mines comprising spraying a water solution of a calcium polysulfide on the surfaces of said mine.

7. A method of treating mercury mines comprising spraying an aqueous mixture of a calcium poly sulfide and a spreading agent on the surfaces of said mine.

8. A method of treating mercury mines comprising spraying an aqueous mixture of calcium polysulfide and an adhesive on the surfaces of said mine.

9. A method of treating mercury mines comprising'spraying an aqueous mixture of calcium polysulfide and wettable sulfur on the surfaces of said mine. v

10. A method of, treating mercury mines comprising spraying an aqueous mixture of calcium polysulfide, a spreading agent, an adhesive and wettable sulfur on the surfaces of said mine.

MERLE RANDALL. 

